Rolling joint mechanisms

ABSTRACT

A rolling joint mechanism consisting of three parts which translates an angular input motion into an output motion of a different form. The parts, comprised of an input member, an output member and a frame, engage each other at specific points along contact surfaces and the points of contact of the three parts are all in a straight line. In addition, substantially pure rolling motion takes place at the engaging surfaces so that the mechanism is substantially free of sliding friction. Finally, the mechanism has the feature that the rolling surfaces may be reshaped so as to allow the mechanism to produce a variety of output motions for a given input motion.

United States Patent Jensen 1 Oct. 10,1972

[54] ROLLING JOINT MECHANISMS [72] Inventor: Preben W. Jensen, 2lSouthside Avenue, Somerville, NJ. 08876 [22] Filed: May 15, 1970 [21Appl. No.: 37,620

[52] US. Cl. ..74/89, 74/89.I7, 74/89.l8, 74/89.2, 74/96, 74/98 [51]Int. Cl ..Fl6h 27/02, Fl6h 29/02, Fl6h 29/20 [58] Field of Search..74/89, 89.2, 96, 98, 89.16, 74/89.l7, 89.18

Primary Examiner-William F. ODea Assistant Examiner-P. D. FergusonAttomey-Sughrue, Rothwell, Mion, Zinn & Macpeak [5 7] ABSTRACT A rollingjoint mechanism consisting of three parts which translates an angularinput motion into an output motion of a different form. The'parts,comprised of an input member, an output member and a frame, engage eachother at specific points along contact sur- 56 R f C'ted l e erences Ifaces and the points of contact of the three parts are UNITED STATESPATENTS all in a straight line. In addition, substantially pure rollingmotion takes place at the engaging surfaces so 2,764,894 10/1956 Faxen..74/89.2 that the mechanism is substantially free of Sliding fric3,046,799 7/1962 Ash et a1 ..74/96 X tioI-L Finally, the mechanism hasthe feature that the Hunkeler ..74/89-2 X rolling surfaces may bereshaped so as to allow the 3,488,098 H1970 Sobczak ..74/89.2 Xmechanism to produce a variety of output motions for a given inputmotion.

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BY WACF-ZQK ATTORNEYS PATENTEDUBT 10 m2 SHEET 3 BF 3 FIG. ll

R 0 I N E V N PREBEN w. JENSEN 7 g Xa-Ku/JZ, 7444A,

ATTORNEYS ROLLING JOINT MECHANISMS BACKGROUND OF THE INVENTION 1. Fieldof the Invention This invention is in the field of art encompassingmotion transferal devices and specifically devices for transferringmotion in which sliding friction is substantially eliminated. 2. PriorArt In prior mechanical and electro-mechanical devices for transformingone form of motion into another, much efficiency, useful life andsensitivity of response were lost by sliding friction. Moreover, since asliding friction force approaches a constant minimum level for normalloading under about grams, the problems it creates increase as the sizeand driving force of the motion transforming devices decrease, as forexample in microminiaturization technology.

The variety of output motions possible with prior art devices utilizingturning joints was very much restricted.

One prior art device sought to provide a motion transformationsubstantially without sliding friction by constraining a cluster ofrotatable members within a guideway having walls spaced apart less thanthe combined diameter of the rotatable members by means of a flexibleband disposed between and partially encompassing the rotatable members.This device, however, could only provide linear output motion due to theconstraining walls.

SUMMARY OF THE INVENTION In view of the limitations of the prior art, itis an object of this invention to provide mechanisms for translatingangular motion into different forms of motion having only substantiallypure rolling friction losses. It is a further object of this inventionto provide a plurality of output motions for a single input motion. Theinvention comprises a rolling joint mechanism consisting of threemembers, one fixed and two movable. Sliding friction is substantiallyeliminated between the engaging surfaces by elements secured to thethree members for insuring point contact between them. The shapes of thethree members depend upon the precise output desired; the only designcriterion for the mechanism being that the points of contact of theengaging surfaces lie on a straight line.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation viewshowing the invention in its basic form.

FIG. 2 is a side elevation view of the invention showing gear teethmeans for constraining point contact at the engaging surfaces.

FIG. 3 is a side elevation view of the invention showing connect bandmeans for constraining point contact.

at the engaging surfaces.

FIG. 4 is an enlarged detached view of connecting band means of FIG. 3.

FIG. 5 is a side view of the arrangement in the direction of the arrows5-5 in FIG. 4.

FIG. 6 is a view of a modification of the invention wherein a pivotreplaces one engaging surface.

FIG. 7 is a view of a modification of the invention showing a differentoutput from the basic invention.

FIG. 8 is a side view of a modification with the two movable membersconstrained for movement on th base by a single band means.

FIG. 9 is a side view of a modification wherein two non-circular rollingmembers are constrained for movement between parallel walls by means ofa single band means.

FIG. 10 is a side view of a modification similar to FIG. 9 but withcurved non-parallel walls.

FIG. 11 is a perspective view of an arrangement similar to FIG. 1 butwith the members disposed in a spherical manner.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows the rolling jointmechanism in its basic form and illustrates the various features andprinciples of this device.

As shown, the rolling joint mechanism consists of an input member 13, anoutput member 17, an input support surface 11 and an output supportsurface 21. The input and output support surfaces may be separatelysupported but are shown in the figures as being commonly supported byframe 9.

The input member 13 is provided with two curved surfaces 8 and 14 andthe output member is also provided with two curved surfaces 16 and 18.Input and output members 13 and 17 contact the frame 9 only at the inputand output surfaces 11 and 21 respectively and they also engage eachother along surfaces 14 and 16. Contact between the members and betweeneach member and its respective support is constrained by means explainedbelow to a point contact in each instance. Thus, all the contact pointsin the mechanism are rolling joints and sliding friction is avoided.

Input member 13 and output member 17 are so designed that when a point15 on the free end of input member 13 is moved a point 19 on the freeend of the output member 17 moves in a straight line. In operation, themechanism functions as follows: when the free end 15 of input member 13is moved the curved surface 8 of input member 13 rolls on the supportsurface 11 at point 25 and the curved surface 14 engages the curvedsurface 16 of output member 17 at point 27 causing the curved surface18. of output member 17 to roll on supporting surface 21 at point 29.Since point 19 on the free end of output member 17 is the central pointof a circular arc point 19 parallels the contour of surface 21 anddefines a straight line. However, the path of point 19 is not restrictedto a straight line but the two surfaces 18 and 21 may be shaped so thatpoint 19 describes any desired path. The other surfaces must then bereshaped according to the desired input-output relationship.

FIG. 2 shows one method for maintaining a non-slip point contact betweenthe engaging surfaces at points 25., 27 and 29. Sets of gear teeth 31,33 and 35 are provided on the engaging surfaces.

FIGS. 3, 4 and 5 show another method for requiring engaging points 25,27 and 29 to be rolling joints. In this method a pair of resilient bandsare fastened between each joint. Since the pairs of bands, indicatedgenerally at 37, 39 and 41 are identical in concept, a discussion ofpair 37 will suffice for all. As is shown in FIG. 4, each band of thepair is fastened at one end to one of the contacting members and at theother end to the other of the contacting members. Thus, resilient band43, for example is fastened by removable fastener 45 to input member 13,tightly stretched to follow the curvature of input member 13 until thepoint of contact and then tightly stretched upon support surface 1 l andremovably fastened thereto by fastener 47. Likewise, resilient band 49is removably fastened to input member 13 by fastener 53, tightlystretched along support surface 11 and removably fastened thereto byfastener 51. The fasteners may be of any suitable type such as screws,snaps, hook, pin and groove or the like. FIG. 5 shows that bands 43 and49 are parallel. The tension on the pair of bands 37 prohibits inputmember 13 from sliding with respect to support surface 11 and thusinsures rolling contact at 25.

FIG. 6 shows a modification of the basic invention wherein one set ofrolling engaging surfaces are replaced by pivot means 55. Although thisreplacement sacrifices some of the friction savings inherent in therolling joint mechanism it adds to the mechanical stability of themechanism and also allows a fixed rotary input to the mechanism.

FIG. 7 shows a modification of the basic invention wherein the outputsupport surface 59 is not linear and thus the point 61 on the free endof output member 57 provides a curved path. The point 61 in FIG. 7 willtrace a curve dependent upon the contour of the support surface 59 andcurved surface 58. Removable fasteners 23 shown both in FIGS. 1 and 7allow support surface 21 of FIG. 1 to be replaced by support surface 59.In FIG. 7, that portion of output member 57 which contacts input member13 at point 27 is also altered so that the three contact points of therolling joint mechanism always define a straight line. Thus, it is seenthat by a suitable device of contacting surfaces, a variety of outputmotions can be produced by the rolling joint mechanism.

Member 13 has been described throughout as the input member and member17 has been described throughout as the output member. Either point 19or point can receive an input and deliver an output and thus thedesignation of members 13 and 17 as input and output member respectivelyis purely for convenience sake and in no way limits the invention.

Although the members having surfaces 11 and 21 have been designated asbeing part of the frame, it is to be understood that these members couldbe arranged in a movable manner and certain previously movable memberscould be fixed to yield new mechanisms. Such a process of changing therole of different members is known in the art as kinematic inversion.

FIG. 8 shows a modification which is somewhat similar to the arrangementshown in FIG. 6, inasmuch as a member 70 having two curved surfaces 72and 74 is disposed in rolling engagement with a stationary base member76 having a curved surface 78 and a movable member 80 pivoted at 82 andprovided with a curved surface 84. The principle difference resides inthe fact that due to the configuration of the intermediate member 70 andthe curved surfaces 78 and 84, a single constraining band 86 may beused. The band 86 may be secured at its opposite ends to the members 76and 80 respectively by any suitable means such as discussed above withrespect to the other arrangements. However, to utilize a single band 86it is essential that the tangent lines at the two points of rollingcontact 88 and 90 intersect on the side of the device where the two endsof the band 86 terminate. The member 80 may be provided with a handle 92of any desired configuration and the member 70 may also be provided withany suitable motion transmitting extension 94.

FIG. 9 shows a modification wherein two rolling members 96 and 98,having a non-circular cross-section, are constrained for rollingmovement by a single band 100 secured at its opposite ends to parallelretaining walls 102 and 104. The spacing between the walls 102 and 104must be less than the sum of the minimum cross-sectional dimensions ofeach of the rolling members 96 and 98 so that these members will beretained in the same relationship to each other between the walls.Suitable motion transmitting arms 106 and 108 may be secured to therolling members 96 and 98 respectively to provide input and outputmovements. Numerous other forms of motion transmitting members may beutilized depending upon the motions involved. The radius of curvature ofthe various points of contact can be chosen so that for a given uniformband the force required to move the members in a longitudinal directioncan be made to vary according to a desired function. This is due to thefact that when the mechanism moves the change in the amount of energystored in the band is dependent upon the radius of curvature of themembers at the different points of contact. The whole mechanism has atendency to assume a position where the amount of energy stored in theelastic band is the least possible.

FIG. 10 shows an embodiment very similar to the embodiment describedabove with respect to FIG. 9 with the exception that the stationarysurfaces 1 10 and l 12 are curved instead of parallel. In order that asingle elastic band 100 may be used to guide the movable members therequirement is that for movable member 96 the tangents at the point ofcontact always intersect at one side of the line through the points ofrolling contact and the tangents at the point of contact for movablemember 98 always intersect on the opposite side of said line.

In all of the foregoing embodiments the basic requirement was that thethree points of rolling contact or the two points of rolling contactplus the pivot point be disposed along a straight line. FIG. 11 shows avariation which provides a spherical rolling joint mechanism. Themovable members and 122 and the stationary surfaces 124 and 126 arearranged in the same basic manner as the members and surfaces of FIG. 1.However, the parts are shaped so as to lie on the surface of a sphere.According to this type of system the basic requirement is that thepoints of rolling contact now lie on a great circle instead of astraight line with the lines of contact intersecting at the center ofthe sphere. The constraining bands have now been shown in FIGS. 1, 6, 7and 11 but it is to be understood that the arrangement of these bands atthe points of rolling contact are similar to the arrangement shown inFIGS. 4 and 5. With respect to FIG. 11 however, the bands will definethe arc of a circle when laid out in planar form due to the sphericalnature of the arrangement.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

What is claimed is:

l. A rolling joint mechanism comprising support means including a firstsupport surface, a first member movably mounted on said support means,said first member having a first curved surface, a second member movablymounted on said first support surface, said second member having firstand second curved surfaces, and constraining means maintaining saidfirst surfaces of said first and second members in rolling contact witheach other while maintaining said second curved surface of said secondmember in rolling contact with said first support surface wherebymovement of one of said members causes movement of the other of saidmembers relative to said support means.

2. A rolling joint mechanism as set forth in claim 1 wherein said firstmember is pivoted on said support means and said constraining means iscomprised of a single band secured to said first support surface andsaid first curved surface of said first member and extending about saidsecond member along the side thereof opposite to the side adjacent theintersection of the two tangent lines through the points of rollingcontact between the first and second members and the second member andfirst support surface.

3. A rolling joint mechanism as set forth in claim 1 wherein saidsupport means further includes a second support surface disposedopposite to said first support surface, said first member being providedwith a second curved surface disposed in rolling contact with saidsecond support surface and said constraining means is comprised of asingle flexible band grouped in a generally S-shaped fashion about saidfirst and second movable members with the ends thereof secured toopposite supporting surfaces; said first and second movable members eachhaving a continuous curved surface of non-circular cross-section.

4. A rolling joint mechanism as set forth in claim 3 wherein saidopposite supporting surfaces are parallel to each other.

5. A rolling joint mechanism as set forth in claim 3 wherein saidopposite supporting surfaces are each curved and the lines tangent tothe points of rolling contact for the first member intersect on the sideof said mechanism opposite the point of intersection of the linestangent to the points of rolling contact of said second member.

6. A rolling joint mechanism as set forth in claim 1 wherein saidconstraining means are comprised of meshing sets of gear teeth disposedalong those curved surfaces arranged in rolling contact with each other.

7. A rolling joint mechanism as set forth in claim 1 wherein said firstmember is pivoted on said support means and said constraining means iscomprised of first and second pairs of flexible bands stretched betweenthe first curved surfaces of the first and second members and betweensaid second curved surface of said second member and said first supportsurface wherein each flexible band of a pair is attached to one surface,tightly stretched upon that surface through the point of contact betweensurfaces and then tightly stretched on the opposite surface and attachedthereto with the flexibl bands in eac air extendin ino osite irections.A rolling jo i n t mechanism as se t forth in claim 1 wherein saidsupport means includes a second support surface and said first member isprovided with a second curved surface disposed in contact with saidsecond support surface and further comprising additional constrainingmeans maintaining said second curved surface of said first member andsaid second support surface in rolling contact with each other.

9. A rolling joint mechanism as set forth in claim 8 wherein saidadditional constraining means is comprised of a meshing set of gearsbetween said second curved surface of said first member and said secondsupport surface.

10. A rolling joint mechanism as set forth in claim 8 wherein saidadditional constraining means is comprised of a pair of flexible bands,each of said flexible bands being attached at one end to said secondsupport surface and at the other end to said second curved surface ofsaid first member with said bands extending in opposite directions.

11. A rolling joint mechanism as set forth in claim 8 wherein all of thepoints of rolling contact are disposed in a straight line.

12. A rolling joint mechanism as set forth in claim 8 wherein all of thepoints of rolling contact are disposed along the arc of a circle.

1. A rolling joint mechanism comprising support means including a firstsupport surface, a first member movably mounted on said support means,said first member having a first curved surface, a second member movablymounted on said first support surface, said second member having firstand second curved surfaces, and constraining means maintaining saidfirst surfaces of said first and second members in rolling contact witheach other while maintaining said second curved surface of said secondmember in rolling contact with said first support surface wherebymovement of one of said members causes movement of the other of saidmembers relative to said support means.
 2. A rolling joint mechanism asset forth in claim 1 wherein said first member is pivoted on saidsupport means and said constraining means is comprised of a single bandsecured to said first support surface and said first curved surface ofsaid first member and extending about said second member along the sidethereof opposite to the side adjacent the intersection of the twotangent lines through the points of rolling contact between the firstand second members and the second member and first support surface.
 3. Arolling joint mechanism as set forth in claim 1 wherein said supportmeans further includes a second support surface disposed opposite tosaid first support surface, said first member being provided with asecond curved surface disposed in rolling contact with said secondsupport surface and said constraining means is comprised of a singleflexible band grouped in a generally S-shaped fashion about said firstand second movable members with the ends thereof secured to oppositesupporting surfaces; said first and second movable members each having acontinuous curved surface of non-circular cross-section.
 4. A rollingjoint mechanism as set forth in claim 3 wherein said opposite supportingsurfaces are parallel to each other.
 5. A rolling joint mechanism as setforth in claim 3 wherein said opposite supporting surfaces are eachcurved and the lines tangent to the points of rolling contact for thefirst member intersect on the side of said mechanism opposite the pointof intersection of the lines tangent to the points of rolling contact ofsaid second member.
 6. A rolling joint mechanism as set forth in claim 1wherein said constraining means are comprised of meshing sets of gearteeth disposed along those curved surfaces arranged in rolling contactwith each other.
 7. A rolling joint mechanism as set forth in claim 1wherein said first member is pivoted on said support means and saidconstraining means is comprised of first and second pairs of flexiblebands stretched between the first curved surfaces of the first andsecond members and between said second curved surface of said secondmember and said first support surface wherein each flexible band of apair is attached to one surface, tightly stretched upon that surfacethrough the point of contact between surfaces and then tightly stretchedon the opposite surface and attached thereto with the flexible bands ineach pair extending in opposite directions.
 8. A rolling joint mechanismas set forth in claim 1 wherein said support means includes a secondsupport surface and said first member is provided with a second curvedsurface disposed in contact with said second support surface and furthercomprising additional constraining means maintaining said second curvedsurface of said first member and said second support surface in rollingcontact with each other.
 9. A rolling joint mechanism as set forth inclaim 8 wherein said additional constraining means is comprised of ameshing set of gears between said second curved surface of said firstmember and said second support surface.
 10. A rolling joint mechanism asset forth in claim 8 wherein said additional constraining means iscomprised of a pair of flexible bands, each of said flexible bands beingattached at one end to said second support surface and at the other endto said second curved surface of said first member with said bandsextending in opposite directions.
 11. A rolling joint mechanism as setforth in claim 8 wherein all of the points of rolling contact aredisposed in a straight line.
 12. A rolling joint mechanism as set forthin claim 8 wherein all of the points of rolling contact are disposedalong the arc of a circle.